This application generally relates to the field of blood glucose measurement systems and more specifically to a test meter comprising a drive mechanism for enabling a test strip to be automatically inserted into a strip port connector for mechanical and electrical connection with the test meter.
Systems that measure analytes in biological fluids, as exemplified by the determination of glucose in blood, typically comprise an analyte meter that is configured to receive a biosensor, usually in the form of a test strip. Because many of these systems are portable, and testing can be completed in a short amount of time, patients are able to use such devices in the normal course of their daily lives without significant interruption to their personal routines. A person with diabetes may measure their blood glucose levels several times a day as a part of a self management process to ensure glycemic control of their blood glucose within a target range.
There currently exist a number of available portable electronic devices that can measure glucose levels in an individual based on a small sample of blood. To perform an assay of the sample, a person is required to prick their finger and provide a blood sample on the test strip. The test strip is then inserted into a test strip port of the test meter to initiate an assay of the sample. Test strips oftentimes may be difficult to manipulate by users due to the small size of the test strips and limitations in the manual dexterity and visual impairment of some users. The user needs to properly align the test strip with the strip port connector and push the test strip in the correct direction to have a proper insertion, which, as mentioned above, can sometimes be problematic for users with dexterity problems. It would therefore be advantageous to provide a test meter that automatically inserts the test strip into its strip port connector.
The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention (wherein like numerals represent like elements).
The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.
As used herein, the terms “patient” or “user” refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment.
The term “sample” means a volume of a liquid, solution or suspension, intended to be subjected to qualitative or quantitative determination of any of its properties, such as the presence or absence of a component, the concentration of a component, e.g., an analyte, etc. The embodiments of the present invention are applicable to human and animal samples of whole blood. Typical samples in the context of the present invention as described herein include blood, plasma, serum, suspensions thereof, and haematocrit.
The term “about” as used in connection with a numerical value throughout the description and claims denotes an interval of accuracy, familiar and acceptable to a person skilled in the art. The interval governing this term is preferably +10%. Unless specified, the terms described above are not intended to narrow the scope of the invention as described herein and according to the claims.
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Specifically, and according to this exemplary embodiment, the user interface buttons 16 include markings, e.g., up-down arrows, text characters “OK”, etc, which allow a user to navigate through the user interface presented on the display 14. Although the buttons 16 are shown herein as separate switches, a touch screen interface on display 14 with virtual buttons may also be utilized. The display 14 may comprise a movable type of display, such as a sliding display or a tiltable display.
The electronic components of the glucose measurement system 100 can be disposed on, for example, a printed circuit board situated within the housing 11 and forming a data management unit 150 of the herein described system 100.
According to this exemplary embodiment, the processing unit 50 is electrically connected to a test strip port connector (“SPC”) circuit 70, that is positioned in the test strip port 22, via an analog front end (AFE) subsystem 72. The analog front end subsystem 72 is electrically connected to the SPC circuit 70 during blood glucose testing. To measure a selected analyte concentration, the SPC circuit 70 detects a resistance or impedance across electrodes of the analyte test strip 24 having a blood sample disposed in a sample chamber 34 therein, using a potentiostat or transimpedance amplifier, and converts an electric current measurement into digital form for presentation on the display 14, typically in units of milligrams per deciliter (mg/dl) or millimoles per liter (mmol/l). The processing unit 50 can be configured to receive input from the SPC circuit 70 via analog front end subsystem 72 over an interface 71 and may also perform a portion of the potentiostat function and the current measurement function.
The analyte test strip 24 can be in the form of a test strip for measuring a glucose concentration, or other analyte appropriate for monitoring of a biological condition, comprising an electrochemical cell, or sample chamber. The test strip 24 is defined by one or more nonporous, non-conducting substrates, or layers, onto which one or more electrodes, or conductive coatings may be deposited. These electrodes may function as working electrodes, reference electrodes, counter electrodes or combined counter/reference electrodes. Additional non-conducting layers may be applied in order to define the planar dimensions of the electrode structure(s). Test strip 24 can also include a plurality of electrical contact pads, where each electrode can be in electrical communication with at least one electrical contact pad. The strip port connector 104 can be configured to electrically interface to the electrical contact pads, using electrical contacts in the form of flexible conductive prongs, and form electrical communication with the electrodes. The test strip 24 can include a reagent layer that is disposed over at least one electrode in the electrochemical cell, including the working electrode. The reagent layer can include an enzyme and a mediator. Exemplary enzymes suitable for use in the reagent layer include glucose oxidase, glucose dehydrogenase (with pyrroloquinoline quinone co-factor, “PQQ”), and glucose dehydrogenase (with flavin adenine dinucleotide co-factor, “FAD”). Enzymes other than those used to determine glucose are also applicable, for example, lactate dehydrogenase for lactate, β-hydroxybutyrate dehydrogenase for β-hydroxybutyrate (ketone body). An exemplary mediator suitable for use in the reagent layer includes ferricyanide, which in this case is in the oxidized form. Other mediators may be equally applicable, depending upon the desired strip operating characteristics, for example, ferrocene, quinone or osmium-based mediators. The reagent layer can be configured to physically transform glucose into an enzymatic by-product and in the process generate an amount of reduced mediator (e.g., ferrocyanide) that is proportional to the glucose concentration. The working electrode can then be used to measure a concentration of the reduced mediator in the form of a current magnitude. In turn, microcontroller 50 can convert the current magnitude into a glucose concentration whose numerical value (in mg/dl or mmol/l) may be presented on the display 14. An exemplary analyte meter performing such current measurements is described in U.S. Patent Application Publication No. US 2009/0301899 A1 entitled “System and Method for Measuring an Analyte in a Sample”, which is incorporated by reference herein as if fully set forth in this application.
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The processing unit 50 may be programmed to activate a test strip drive mechanism in response to receiving the signal from the proximity detector 67. In one embodiment, the test meter 10 may remain in a sleep or passive mode until the meter 10 is activated by the signal from the proximity detector 67. In one embodiment, the drive mechanism comprises a motor 52 connected to a motor drive 51, or motor controller, which regulates a direction and speed of the motor 52 via programmed control signals which are transmitted by the processing unit 50. According to the herein described embodiment, a gear box 53, or gear assembly, is attached to the output of the motor 52 for stepping down the rotation drive ratio generated by the motor 52. Attached to the gear box 53 via a drive shaft 80, is a rotatable drive wheel 54, which may comprise a substantially rigid rim covered by a rubber or other suitably compliant layer, or the drive wheel 54 may be comprised mostly of rubber or compliant material sufficient to provide traction when the drive wheel 54, during rotation, physically contacts a portion of the test strip 24 in order to pull the test strip 24 into the test strip port 22 and into engagement with the SPC circuit 70.
A display module 58, which may include a display processor and display buffer, is electrically connected to the processing unit 50 over the communication interface 57 for receiving and displaying output data, and for displaying user interface input options under control of processing unit 50. The display interface is accessible by processing unit 50 for presenting menu options to a user of the blood glucose measurement system 100. User input module 64 may receive responsive inputs from the user manipulating buttons, or keypad 16, which are processed and transmitted to the processing unit 50 over the communication interface 63. The processing unit 50 may have electrical access to a digital time-of-day clock connected to the printed circuit board for recording dates and times of blood glucose measurements and user inputs, which may then be accessed, uploaded, or displayed at a later time as necessary.
An on-board memory module 62, that includes but is not limited to volatile random access memory (“RAM”), a non-volatile memory, which may comprise read only memory (“ROM”) or flash memory, and may be connected to an external portable memory device via a data port 13, is electrically connected to the processing unit 50 over a communication interface 61. External memory devices may include flash memory devices housed in thumb drives, portable hard disk drives, data cards, or any other form of electronic storage device. The on-board memory can include various embedded applications executed by the processing unit 50 for operation of the analyte meter 10, as explained herein. On board or external memory can also be used to store a history of a user's blood glucose measurements including dates and times associated therewith. Using the wireless transmission capability of the analyte meter 10, or the data port 13, as described herein, such measurement data can be transferred via wired or wireless transmission to connected computers or other processing devices.
A communications module 60 may include transceiver circuits for wireless digital data transmission and reception, and is electrically connected to the processing unit 50 over communication interface 59. The wireless transceiver circuits may be in the form of integrated circuit chips, chipsets, and programmable functions operable via processing unit 50 using on-board memory, or a combination thereof. The wireless transceiver circuits may be compatible with different wireless transmission standards. For example, a wireless transceiver circuit may be compatible with the Wireless Local Area Network IEEE 802.11 standard known as WiFi. A transceiver circuit may be configured to detect a WiFi access point in proximity to the analyte meter 10 and to transmit and receive data from such a detected WiFi access point. A wireless transceiver circuit may be compatible with the Bluetooth protocol and is configured to detect and process data transmitted from a Bluetooth “beacon” in proximity to the analyte meter 10. A wireless transceiver circuit may be compatible with the near field communication (“NFC”) standard and is configured to establish radio communication with, for example, an NFC compliant master device in proximity to the analyte meter 10. A wireless transceiver circuit may comprise a circuit for cellular communication with cellular networks and is configured to detect and link to available cellular communication towers.
A power supply module 56 is electrically connected to all modules in the housing 11 and to the processing unit 50 to supply electric power thereto. The power supply module 56 may comprise standard or rechargeable batteries, or an AC power supply that may be activated when the analyte meter 10 is connected to a source of AC power. The power supply module 56 is also electrically connected to processing unit 50 over the communication interface 55 such that processing unit 50 can monitor a power level remaining in a battery of the power supply module 56.
In addition to connecting external storage for use by the analyte meter 10, the data port 13 can be used to accept a suitable connector attached to a connecting lead, thereby allowing the analyte meter 10 to be connected to an external device such as a personal computer. Data port 13 can be any port that allows for transmission of data, power, or a combination thereof, such as a serial, USB, or a parallel port.
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In one embodiment, a drive wheel 54 comprising a smooth, compliant surface for making contact with the test strip 24, and having a width greater than the width of the test strip, such that the sides of the drive wheel 54 extend beyond both side edges of the test strip 24, could be used to form a sample fluid barrier, or sealing feature, to prevent the sample applied to the test strip from leaking into the strip port connector circuit 70. The test strip 24 would fit snugly between a pair of guide rails 69 at the lateral sides of the strip, reducing available channels for fluid contamination to flow past the drive wheel 54 towards the strip port connector circuit 70. The height of the drive wheel 54 above the test strip 24 and the height of the guide rails 69 may be selected so that the drive wheel 54 makes contact with the upper surface of the test strip 24 when inserted, while not rubbing against the guide rails. The pressure from the drive wheel 54 against the test strip 24 in conjunction with the guide rails 69 serves to confine any leaked sample fluid away from the strip port connector circuit 70. In addition, the test strip 24 itself may be modified to facilitate traction against the drive wheel 54. Although the engaged test strip 24 may be essentially planar, a top layer of the test strip 24, i.e. the surface upon which the drive wheel makes contact, may further include at least one feature such as nubs, or cross-wise grooves, or other protruding or recessed physical features that could cooperate with the engaging drive wheel 54 to aid in retraction and/or ejection of the test strip 24.
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As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a processing system, method, or apparatus. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.), or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “circuitry,” “module,” “subsystem” and/or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.
Program code and/or data representative of operations and measurements performed may be stored using any appropriate medium, including but not limited to any combination of one or more computer readable medium(s). A computer readable storage medium may be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible, non-transitory medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code and/or data representative of operations and measurements performed may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
While the invention has been described in terms of particular variations and illustrative figures, those of ordinary skill in the art will recognize that the invention is not limited to the variations or figures described. In addition, where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Therefore, to the extent there are variations of the invention, which are within the spirit of the disclosure or equivalent to the inventions found in the claims, it is the intent that this patent will cover those variations as well.